M illiam pere-m eter



(No Model.)

C. M. HOLLOPETBR. MILLIAMPERE METER. i

No. 559,134. PatentedAprQ 28, 1896.

FIG.|.

ull 1 lil u lr w 4l ll ll MUN" i n UNITED STATES PATENT OFFICE.

CHARLES M. HOLLOPETER, OF FOSTORIA, OHIO.

IVIILLIAIVI PERE-METER.

SPECIFICATION forming part of Letters Patent No. 559,134, aatdnprn 2e, 189e." Application filed May 31, 1895. `Serial No. 551,181. (No model.)

To all whom t 71mg/ concern.-

Be it known that l, CHARLES M. HOLLO- PETER, a citizen of the United States, residing at Fostoria, in the county of Seneca and State of Ohio, have invented a new and useful Milliampere-Meter, of which the following is a specification. A e

This invention relates to electrical measuring instruments; and it has for its object to provide a new and useful instrument of this character especially adapted for the measurement of galvanic currents that are appliedto the human body as a therapeutic agent and the registering of such currents in milliarneres.

To this end the main and primary object of the present invention is to construct a milliampere-meter that shall be extremely simple, while at the same time very sensitive to the inuence of the electric current, wh ereby the current can be measured with the greatest degree of accuracy in milliamperes.

The invention also contempla-tes a specific manner of mounting the instrument, whereby the same can be read with the greatest facility and can be adjusted in various positions without affecting the delicate operation thereof, and in the attainment of this object the instrument is particularly adapted for the use of the physician.

With these and other objects in view, which will readily appear as the nature of the invention is better understood, the same consists in the novel construction, combination, and arrangement of parts hereinafter more fully described, illustrated, and claimed.

In the drawings, Figure l is a front elevation of amilliampere-meter constructed in accordance with this invention. Fig. 2 is a similar view thereof, partly in section. Fig. is a central vertical sectional view of the instrument. Fig. 4 is a central horizontal sectional view thereof on line ce a; of Fig. 2. Fig. 5 is a detail in perspective of the indicating-needle and its attachments. Fig. 6 is a detail in perspective of one of the spring retaining-plates. 4

Referring to the accompanying drawings, l designates a circular casing fitted on the circular base-block 2 and provided with a glass front 3, through which front the readings are made. The circular base-block 2,

that supports the circular casing l., is preferably mounted for adjustment on the bracketarm a. The bracket-arm a is substantially L-shaped, andthe extremity of the horizontal portion is reduced, as at 5, and is swiveled centrally in the circular base-block 2, so that the casing can be readily rotated or turned axially in order to correct the position ofthe indicating-hand when necessary. The vertical portion of the bracket-arme is adapted to be loosely mounted in an upright tubular socket 6, that is adapted to be secured on a base-board or other convenient vpoint of attachment where the instrument is designed to be used. By reason of mounting the bracket-arm in the upright tubular socket it will be obvious that the instrument can be swung laterally from side to side, and in this connection the instrument is especially useful to the physician, inasmuch as the same can be turned to the very position in which it is most convenientto make the readings while operating upon a patient with the electric current that is measured by the instrument.

The circular base-block 2 of the casing is preferably provided in the front side thereof with a recess 7, in which is arranged the vertically-disposed elliptical core 8. The elliptical core 8 is made of brass or other suitable metal and is provided with a depending attaching-ange 9, that receives the screws 10, which aiford convenient means for securing thecoreto the front side of the base-block and within the recess thereof. The core 8 is arranged so that the open axis thereof is disposed vertically and is provided with the opposite open sides l1, which open sides provide for the easy induction of the electric current upon the magnetic bar-armature 12, that is arranged inside of the hollow elliptical coro 8 with its ends disposed in proximity to the opposite curved ends of the core, and by this arrangement within the hollow core the magnetic bar-armature l2l is susceptible to the slightest influence'of the electric current and is thereby easily and positively deflected. The core 8 is encircled by the magnetizing helix or coil 13, the terminals of which are IOO connected to the binding-posts 14, iitted to the rear side of the base-block 2, which binding-posts are adapted to have connectedtherewith the circuit-wires of a galvanic battery and the electrodes or other devices employed in connection therewith.

The magnetic bar-armature 12, that is arranged longitudinally within the hollow elliptical core S, is attached in a horizontal position to a supporting disk or plate 15, in which disk or plate 15 is fitted a bearing-plate 16, which extends to both sides of the disk or plate 15 and is beveled at its lower edge '-to a knife-bearing edge 17. The opposite ends of the knife-edge bearing-plates 16 rest in the V-shaped bearing-notches 18, formed eentrally in the opposite upper sides of the core 8. The ends of the bearing-.plates 16, that are delicately poised in the bearing-notches 18, are securely retained in position within such notches by means of spring retainingplates 19. The spring retaining-plates 19 are secured fast at one end to the opposite upper sides of the core S, and the free ends of said springs are disposed directly over the notches 18 to close in such notches and prevent the dislocation of the ends of the bearing-plate 16. At their free ends over the notches 1S the plates 19 are provided at one side with the depending anges 20, having curved lower edges 2la disposed directly over the upper edge of the plate 16 to form an additional bearing for such plate and hold the same perfectly steady within the notches 1S.

The supporting disk or plate l5, that carries the bar-armature 12, which is preferably made of spring-steel, also has attached thereto the lower end of the indicating-needle 21, which plays over the face of the crescentshaped dial-plate 22, arranged on the front face of the base-block 2 and provided with a curved scale 23, that is graduated in milliamperes, so that the readings will be made entirely in milliamperes. The indicating-needle 21 is designed to play from end to end ofthe vscale 23 and is limited in its extreme movements by the spaced stop-pins 24, projected from the front side of the block 2. The opening of the crescent-shaped dial-plate 22 and the recess of the block 2, in which the helix and its core are arranged, are covered from View by a sheet 25, of dark celluloid or the like, secured on the lower part of the glass front 3 of the casing 1.

The indicating-needle 2l is provided near its lower end with an' angled portion 26, on which is arranged a movable weight 27, that is adapted to be adjusted to the resistance, so that the needle can be regulated to traverse the dial-plate fast or slow at pleasure, and at this point it will be noted that the lower 'end of the indicating-needle is connected to the supporting disk or plate 15 at one side of the bearing-support therefor.

From the vabove it is thought that the advantages and operation of the kherein-described milliampere-meter will be readily nnderstood by those skilled in the art, and it will be also understood that changes in the form, proportion, and the minor details of said socket and provided at the extremity of its horizontal portion with a reduced portion swiveled centrally in the back of the easing, substantially as set forth.

2. In a milliampere-meter, the casing having a dial-plate, a hollow elliptical core arranged within the casin g, the helix or coil su rrounding the core, and an indicating-needle pivotally supported at its lower end on the core and carrying a magnetic bar-armature disposed longitudinally within the core, substantially as set forth.

3. In a milliampere-meter, the dial-plate, an elliptical hollow core provided with opposite open sides, an indicating-needle pivotally mounted on the core and carrying a magnetic bar-armature arranged longitudinally within the core, and the helix or coil for the core, substantially as set forth.

4. In a milliampere-meter, the casing having a dial-plate, a hollow elliptical electromagnet, a supporting disk or plate pivotally supported within the magnet and carrying a horizontal magnetic bar-armature disposed longitudinally Within the magnet, an indicating-needle provided at its lower end with an angled portion attachedto said supporting disk or plate at one side of the pivotal sup- 'port therefor, and a movable weight mounted to slide on the angled portion of the needle, substantially as set forth.

5. In a milliampere-meter, the casing having a dial-plate, a hollow elliptical electromagnet, the core of which is provided in its opposite upper sides with V-shaped bearingnotches, a supporting disk or plate carrying a horizontal magnetic bar-arm ature arranged longitudinally within the magnet, a knifeedge bearing-plate itted to the supporting disk or plate and resting at its ends in said V- shaped bearing-notches, an indicating-needle attached at its lower end to the supporting disk or plate at one side of its pivotal support, and the spring retaining-plates secured at one end to opposite upper sides of the core of the magnet and disposed at their free ends over said bearing notches, substantially as set forth.

ln testimony that I claim the foregoing as my own I have hereto affixed my signature in the presence of two witnesses.

CHARLES M. HOLLOPETER.

Titnessesz JOHN J. LEHMANN, DAVID HALEs.

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